Afterburners

Military supersonic aircraft utilize an afterburner that acts as an additional combustion element in the jet engine. This significantly increases the thrust of a jet engine for shorter periods which is necessary while taking off, climbing, or within a battleground.

Backdrop of Afterburning

An Italian Engineer designed a motor jet named Caproni Campini C.C.2. The first-ever afterburner was incorporated in it. Later on, in the 1950s, afterburners came to be used widely in military aircraft and a handful of commercial planes. Early British days witnessed the reheat work on a Rolls-Royce W2/B23. This eventually led to the “dump and burn” feature in which the fuel is jettisoned and ignited using the afterburner.

How it works

The purpose of installing an afterburner is to achieve an increment in the power of an afterburner jet. However, the perks are available for shorter durations as it leads to greater fuel consumption and increased mass and frontal area. Afterburners are also referred to as ‘anode gas oxidizers’.

Excess air is allowed to flow inside a turbine engine where the fuel burns generating an ample quantity of oxygen to continue combustion. Thus, there is always the option of inducing additional fuel to burn downstream of the turbine. The whole process boosts the thrust of the afterburner jet engine. While in action, the resulting discharge gas due to a very high afterburner temperature (1700 degrees C) is permitted to flow along the jet pipe wall to maintain a safe temperature. The pipe size of an afterburner is larger compared to a normal jet pipe to reduce the pressure and velocity of the gas stream. In low by-pass engines, afterburning is achieved by mingling the by-pass and turbine fuels before injecting the afterburner fuel. An alternative technique encourages stabilizing the flame in both the by-pass and turbine streams individually by setting a common exit temperature of the available gases. The fuel cells consume 60-85% of the fuel leaving the rest in afterburners.

Advantages of Afterburners

1. To design a flame burner that can operate in all modes (start-up, partial and full transients) is a challenge to aerospace engineers.
2. Less prone to sensitivity from catalyst poisons and sintering.
3. Ensures thermal protection measures.

Disadvantages of Afterburners

1. Catalytic burners are designed easily compared to afterburners.
2. Afterburners have limitations when it comes to the composition range of fuels.
3. The cyclic operation involving high temperature and critical gas composition inside the burner requires quality thermal corrosion resistance.

Falcon 20 

Falcon 20 manufactured by Dassault Aviation is a business jet aircraft. The Falcon enterprise was first introduced on 3rd June 1965. To date, 512 specimens have been produced. Currently, the production is stopped. The cabin dimensions of height 5’7″, width 6’1″, and length 24′ bring this under a super midsize jet. Though F20 turns up to be a more preferable option compared to its competition: the Hawker 800 when we consider the luggage space. The falcon 20 afterburner contributes to achieving a touring velocity of 685 mph subject to headwinds, high altitude, and hot temperature. The Falcon 20-F-5BR represents the latest generation of the private jet line business. Recent news has surfaced the production confirmation of Falcon 10X which is set to launch in the year 2025. This jet priced at USD 75 million is a successor of Falcon 8X. The technology introduced in these jets ensures a safer and slower landing speed.

Afterburner Jet

Afterburner jets have an extra fuel section storing additional fuel injectors. Quite similar to a rocket, a jet engine is also a reaction engine. It burns fuels with air from the surrounding atmosphere. The required thrust is generated as the nearby hot air expands and shoots out of a nozzle. This is how the jet takes off. As the jet nozzle must be bigger while using an afterburner, an automatic, adjustable nozzle is a mandatory element in the system.

Modern jets use turbines to reduce the load of engines. This efficiency saves a lot of oxygen. So, afterburners can be utilized to burn this air and inject fuel in the exhaust stream causing an increase in thrust by half of its potential. The thrust generated after afterburning can shoot up to 16000 lbf (7100 N). Afterburners can operate for up to 12 minutes at full strength. Shock waves are formed when exhaust gases are released at a supersonic speed from an afterburner jet. This leads to the loud noise of burners. Commercial planes avoid afterburners due to high fuel consumption and noise.

Conclusion

An afterburner appears as an extension at the back of a jet engine. They provide additional thrust utilizing the remaining oxygen to burn fuel in the high-speed exhaust stream released from the turbine.

This device is installed inside a tailpipe of a turbo engine for injecting fuel into the hot exhaust stream. In the automobile, it catalytically destroys partially burned carbon compounds in the exhaust. In an F1 race, racers use afterburners to accelerate out of the corners and take advantage of their opponents.

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